fftools/ffmpeg_mux: print latency information in -debug_ts muxing output

doc/ffmpeg.texi

@@ -830,7 +830,7 @@ be achieved with @code{ffmpeg ... < /dev/null} but it requires a
 shell.
 
 @item -debug_ts (@emph{global})
-Print timestamp information. It is off by default. This option is
+Print timestamp/latency information. It is off by default. This option is
 mostly useful for testing and debugging purposes, and the output
 format may change from one version to another, so it should not be
 employed by portable scripts.

fftools/ffmpeg_mux.c

@@ -25,10 +25,12 @@
 #include "ffmpeg_utils.h"
 #include "sync_queue.h"
 
+#include "libavutil/avstring.h"
 #include "libavutil/fifo.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/log.h"
 #include "libavutil/mem.h"
+#include "libavutil/time.h"
 #include "libavutil/timestamp.h"
 
 #include "libavcodec/packet.h"
@@ -59,6 +61,80 @@ static int64_t filesize(AVIOContext *pb)
     return ret;
 }
 
+static void mux_log_debug_ts(OutputStream *ost, const AVPacket *pkt)
+{
+    static const char *desc[] = {
+        [LATENCY_PROBE_DEMUX]       = "demux",
+        [LATENCY_PROBE_DEC_PRE]     = "decode",
+        [LATENCY_PROBE_DEC_POST]    = "decode",
+        [LATENCY_PROBE_FILTER_PRE]  = "filter",
+        [LATENCY_PROBE_FILTER_POST] = "filter",
+        [LATENCY_PROBE_ENC_PRE]     = "encode",
+        [LATENCY_PROBE_ENC_POST]    = "encode",
+        [LATENCY_PROBE_NB]          = "mux",
+    };
+
+    char latency[512];
+
+    *latency = 0;
+    if (pkt->opaque_ref) {
+        const FrameData *fd = (FrameData*)pkt->opaque_ref->data;
+        int64_t         now = av_gettime_relative();
+        int64_t       total = INT64_MIN;
+
+        int next;
+
+        for (unsigned i = 0; i < FF_ARRAY_ELEMS(fd->wallclock); i = next) {
+            int64_t val = fd->wallclock[i];
+
+            next = i + 1;
+
+            if (val == INT64_MIN)
+                continue;
+
+            if (total == INT64_MIN) {
+                total = now - val;
+                snprintf(latency, sizeof(latency), "total:%gms", total / 1e3);
+            }
+
+            // find the next valid entry
+            for (; next <= FF_ARRAY_ELEMS(fd->wallclock); next++) {
+                int64_t val_next = (next == FF_ARRAY_ELEMS(fd->wallclock)) ?
+                                   now : fd->wallclock[next];
+                int64_t diff;
+
+                if (val_next == INT64_MIN)
+                    continue;
+                diff = val_next - val;
+
+                // print those stages that take at least 5% of total
+                if (100. * diff > 5. * total) {
+                    av_strlcat(latency, ", ", sizeof(latency));
+
+                    if (!strcmp(desc[i], desc[next]))
+                        av_strlcat(latency, desc[i], sizeof(latency));
+                    else
+                        av_strlcatf(latency, sizeof(latency), "%s-%s:",
+                                    desc[i], desc[next]);
+
+                    av_strlcatf(latency, sizeof(latency), " %gms/%d%%",
+                                diff / 1e3, (int)(100. * diff / total));
+                }
+
+                break;
+            }
+
+        }
+    }
+
+    av_log(ost, AV_LOG_INFO, "muxer <- pts:%s pts_time:%s dts:%s dts_time:%s "
+           "duration:%s duration_time:%s size:%d latency(%s)\n",
+           av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &ost->st->time_base),
+           av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &ost->st->time_base),
+           av_ts2str(pkt->duration), av_ts2timestr(pkt->duration, &ost->st->time_base),
+           pkt->size, *latency ? latency : "N/A");
+}
+
 static int write_packet(Muxer *mux, OutputStream *ost, AVPacket *pkt)
 {
     MuxStream *ms = ms_from_ost(ost);
@@ -140,16 +216,8 @@ static int write_packet(Muxer *mux, OutputStream *ost, AVPacket *pkt)
 
     pkt->stream_index = ost->index;
 
-    if (debug_ts) {
-        av_log(ost, AV_LOG_INFO, "muxer <- type:%s "
-                "pkt_pts:%s pkt_pts_time:%s pkt_dts:%s pkt_dts_time:%s duration:%s duration_time:%s size:%d\n",
-                av_get_media_type_string(ost->type),
-                av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &ost->st->time_base),
-                av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &ost->st->time_base),
-                av_ts2str(pkt->duration), av_ts2timestr(pkt->duration, &ost->st->time_base),
-                pkt->size
-              );
-    }
+    if (debug_ts)
+        mux_log_debug_ts(ost, pkt);
 
     if (ms->stats.io)
         enc_stats_write(ost, &ms->stats, NULL, pkt, frame_num);